Process for making usable waste paper containing bitumens



United States Patent of New Jersey Ne Drawing. Filed Oct. 16, 1961, Scr.No. 145,501 3 Claims. (Cl. 1625) The present invention relates to aprocess of deasphaltizing waste paper stock containing asphalt, and/orridding the waste paper of similar contaminants. More specifically thepresent invention relates to a process of rendering asphalt and/orsimilar materials ineffectual in paper stock.

In the manufacture of folding boxboard and other paper products fromwaste paper, it is desirable and economical to use papers containingasphalt and/ or other contaminants. However, the use of such papersrequires special handling, and has caused some paper mills to installexpensive equipment.

Asphalt is used in paper as a laminating medium for two or more plies ofpaper. It is also found in heavy duty waterproof wrap with two or moreplies of asphalt emulsion saturated sheets laminated with asphalt.Asphalt is also found in paper in a wide range of particle sizesdispersed throughout the corrugating grade, multiwall bags and Wrappingpaper.

In nature asphalt is found in bituminous materials. It is primarilycomposed of (a) asphaltenes, which are insoluble in low boilingsaturated hydrocarbons, and which are soluble in carbon tetrachloride;and (b) maltenes, which are soluble in low boiling hydrocarbons. Theasphaltenes are the micells and form from 70% to 90% of the totalasphalt content; and, the maltenes constitute the intermicellar liquid.

It is an object of the present invention to provide a novel process ofmaking asphalt containing waste papers usable by chemical treatmentwithout any additional outlay for extra equipment.

It is a further object to provide a process for ridding waste paper orpaper stock of asphalt and/or similar contaminants.

According to the present invention it has been discovered that wastepaper, or paper stock containing asphalt and/or contaminating materials,e.g. tar, wax, and hydrocarbons, can be chemically treated, and theasphalt content in said paper thereby rendered ineffectual. This isaccomplished by first dissolving the asphalt and/ or contaminants in thesaid paper stock with a suitable solvent; adding a stabilizer to saidpaper stock containing the dissolved asphalt to prevent agglomeration ofthe asphalt and/or contaminant; and finally evaporating the solvent fromthe paper stock so as to leave the contaminants dispersed in the paperstock as microscopic particles.

Asphalt is completely soluble in aromatic hydrocarbons such as xylene,toluene, heavy aromatic naphtha and Solvesso 100 and 150, manufacturedby Humble Oil and Refining Company, and comprise aromatics of 9 and 10carbon atoms plus a small percent of indans, and toluene, xylene, someheavier aromatics and indans, respectively. However, because of theinsolubility of the asphaltene fraction in low boiling saturatedhydrocarbons, only partial solubility of the total asphalt particleoccurs in such aliphatics as heptane, Varsol I, manufactured by HumbleOil and Refining Co., and Solvasols, manufactured by Mobile Oil Co.Varsol I is a combination of aromatics, olefins and saturatedhydrocarbons and Solvasols is a combination of 8-12 carbon atomaromatics and 8-14 carbon atom aliphatics.

In carrying out this invention, an aliphatic type of solvent ispreferably used as the solventrnedia, even though the solvent media doesnot dissolve the total asphalt particle or containment. The primaryfunction of this type of solvent is to dissolve the maltene part of theasphalt leaving the undissolved asphaltene in an easily dispersiblestate.

Also, according to the present invention, a certain minimumconcentration of solvent is required before any appreciable attack onthe asphalt is noted. The con centration of the solvent in the system isbest expressed as a function of water volume rather than as a functionof the asphalt concentration. For example, it was diS- covered thatequal volumes of solvent would act differently on equal amounts ofasphalt at different consistencies, i.e. based on percent dry fiber ofthe total weight. Satisfactory results were obtained at the higherconsistencies, whereas, at the lower consistencies, the asphalt was notfully attacked. In the case of the lower consistencies, the solventmight be considered as being lost as immiscible droplets in the largevolume of Water. In addition, there are differences in the behavior ofaliphatic and aromatic hydrocarbons with regard to the concentrationrequirement through change in asphalt concentration at a fixedconsistency. For example, when the aliphatics are used as the solventmedia, very little extra solvent is needed as the asphalt concentrationis increased from to 3%, based on dry fiber weight. Whereas, when anaromatic is used as the solvent, increased amounts of asphalt must beaccompanied proportionately by increasing the amount of solvent. Onepossible explanation is that the aromatic, being a complete asphaltsolvent, becomes tied up in the dissolution of the asphalt reaction,whereas the aliphatic does not become so involved.

A more detailed explanation brings in the factor of interfacial tensionbetween the solvent and water medium, and the existence of a toughaqueous film surrounding the asphalt particle. As a result of theinterfacial tension, the solvent tends to assume the minimum sizeconsistent with the volume of the solvent; and, under agitation thesolvent is dispersed as droplets throughout the water'medium. Thus, theanalogy that the solvent is lost in a large volume of water and cannotseek out and attack the asphalt below a minimum solvent concentration.

Similar to the restrictive tension between the solvent and water mediato the aqueous film surrounding the asphalt particle, is the presence ofphysical forces that prevents the solvent from attacking the asphalt atconcentrations below a certain minimum peculiar to the particularsolvent. Therefore, it is logical to cause a breakdown of theinterfacial tension in the system so as to allow the solvent to comeintointimate contact with the asphalt. The interfacial tension is brokendown through the use of surface active agents.

The use of surfactants, or surface active agents, can effect a reductionof as much as 50% of the solvent requirements by reducing theinterfacial tension of the system, thus allowing the solvent to comeinto intimate contact with the asphaltic particles. Several surfaceactive agents can be successfuly used, for example, tall oil fatty acid,sodium sulphonate, or polyethylene glycol alkyl aryl ether, also knownas Triton X-100. Other surface active agents of the general nature ofthe fore-mentioned surface active agents can also be used. In all cases,approximately 5% surface active agent, based on the solvent volume, issufiicient to reduce the inter-facial tension so that intimate contactof the solvent with the asphalt is readily achieved. 7 ii I Q As waspreviously discussed,*th e use of surface active agents greatly affectsthe solvent requirements since previous to the use or surface activeagents, certain minimum concentrations had to be attained before theasphalt was attacked. For example, in a fresh water system before theasphalt was attacked, 0.7% Sovasols, based on the water volume, wasrequired to treat 1% asphalt based on the fiber content of the stockpaper. Under similar conditions, when 5% Triton X-100 was added, basedon the solvent volume, it was found that only 0.4% Sovasols was requiredto treat the asphalt. However, an extremely important point regardingthe effect of a surfactant in this de-asphalting system is that when theamount of surface activation goes beyond the initial amount whichreduces the interfacial tension, the solvent tends to become ineffectiveagainst the asphalt. One possible explanation of this effect is that thesolvent becomes the internal phase of an oil in water emulsion and thusloses it identity as a solvent.

Thuaaccording to this invention asphalt can be economically dissolved inthe first phase of this process by the use of surface active agents,which phase is primarily intended, as was previously disclosed, todisperse the asphalt from asphalt containing kraft paper. However, thedispersed asphalt has a tendency to re-agglomerate, and therefore, inorder to prevent the asphalt from reagglomerating, even after the thirdphase of this process has been completed, i.e. evaporation of thesolvent, a chemical stabilizer such as potassium hydroxide is added tothe dissolved asphalt containing mixture. The addition of the chemicalstabilizer to the paper slurry, containing the asphalt contaminantconstitutes the second phase of this invention.

Other chemical stabilizers which can be used in the stabilization phaseaccording to this invention are inorganic metallic hydroxides which havea tendency to react as saponifiers. The preferred stabilizer for thisprocess is sodium hydroxide.

The pH range of the stabilization reaction is also important to thisinvention since at a pH of approximately 11.0 to 13.0, the asphalt willtend to re-agglomerate into particles as large as inch in diameter. At apH range of approximately 8.0, an emulsion will be formed. At a pH rangeof 9.0 to 10.0, the exact or desired dispersion can be obtained. Thepreferred pH range is between 8.5 and 9.5.

Since during the reaction period the pH has a tendency to drop, thedesired pH can be maintained by periodic incremental additions of alkalimetal hydroxide to the pulped waste paper mix being treated.

The final phase of this invention comprises evaporating the solvent fromthe pulped paper mix so as to leave the asphalt or the contaminantdispersed in said paper as microscopic particles. This final evaporationphase can be conducted in any suitable manner, as for example withsteam. The evaporation of the solvent usually takes place when thetemperature has reached approximately about 200 F. Therefore, during thedefibering of the paper stock the temperature must be maintainedsufficiently low so that the solvent does not evaporate from the system.

The asphalt particles which are formed by this process can beelectrostatically precipitated on the fiber with alum or any othersuitable reagent, thus allowing the asphalt particles to leave thesystem via the paper web, or leave the paper web by being trapped by thefiber mat as the paper is being formed onto the cylinder. The resultingsheet appears clean to the eye, however, under microscopic examination,minute particles of asphalt can be seen dispersed throughout the sheet.

The following examples are intended to illustrate the present invention.These examples are inserted without any view of limiting the invention.It not otherwise stated, the parts indicated in the examples are partsby weight.

Example I A standard pulper was loaded with 1,800 pounds of asphaltcontaining Kraft paper. 3,000 gallons of water were added to adjust theconsistency to 6.7% after which steam was added. The stock was thenpulped for about 20 minutes; and, the temperature at this time was aboutF. After pulping 0.5% Varsol I based on the water volume, was added tothe pulper, followed by addition of a sufiicient amount of caustic tobring the pH in the range of 9.0 to 9.5. The temperature was constantlyraised from the end of the pulping cycle so that in the 45 minutes fromthe time the solvent had been added,

the temperature reached approximtaely 200 F., thereby causing theevaporation of the solvent. The pH exhibited a tendency to declineduring the pulping cycle thereby requiring intermittent additions ofcaustic.

Example II A standard pulper was loaded with 1,800 pounds of asphaltcontaining kraft to which 3,000 gallons of water were added, followed bythe addition 020% Triton X-100. The pulper was then started and steamwas added. After 20 minutes the paper stock was defibered and thetemperature of the pulper reached P. wherein 0.4% Sovasols based on the3,000 gallon volume of water was added to the system. Enough caustic wasadded to raise the pH to 9.3. The pulper was restarted and steam againwas added at a rate so that the temperature was raised from 160 F. to200 F. within 45 minutes. The pH exhibited a tendency to drop, but wasmaintained between a pH 8.8 and 9.3 by incremental additions of caustic.

Exampie III A standard pulper was loaded with 1,800 pounds of asphaltcontaining kraft to which 3,000 gallons of Water were added to adjustthe consistency to 63%, after which the pulper was started and the steamwas added. By the end of 20 minutes the stock had been defibered and thetemperature had reached 150 F. The pulper was then stopped and 0.7%Sovasols, based on the water volume, was added along with a solution ofKOH to pH 9.5. The pulper was restarted and steam was again added at avrate so that the temperature was raised from 150 to 200 F. within 45minutes. The 200 temperature was maintained until the solvent odor wasabsent from the steam vapors coming from the pulper mix. During thereaction period the pH exhibited a tendency to drop, but was maintainedbetween about .5 and 9.5 through period incremental additions of XOR.

it is to be noted that water is added to the pulper containing the krattpaper to be treated so that the consistency of the paper is adjustedbefore steam is added to the system. The preferred adjusted consistencyis approximately 6.7% based on the weight of the lzraft paper to betreated.

It should also be noted that when this process is used, there isabsolutely no danger from build-up of asphalt, even when a closed whitewater system is used; and, the odor of the solvent is completelyeliminated.

While the invention has been described with particular reference tospecific embodiments, it is to be understood that it is not to belimited thereto, but is to be construed broadly and restricted solely bythe scope of the appended claims.

I claim:

1. A process for making waste paper, which contains bituminouscontaminants, usable by chemical treatment, comprising the steps of:

(a) dissolving the contaminants from said waste paper with an aliphatichydrocarbon;

(b) adding an alkali metal hydroxide as a stabilizer to the solution ofcontaminants, in an amount to result in a pH range of about 8.5 to about9.5; while maintaining the temperature in steps (a) and (b) below theboiling point of said hydrocarbon; and

(c) heating the hydrocarbon solution to approximately 200 F.,evaporating sufiicient solvent to cause the contaminants to becomedeposited as microscopic particles in dispersion in the waste paper.

2. A process for making waste paper, which contains asphaltcontaminants, usable by chemical treatment, which comprises the stepsof:

(a) dissolving the asphalt from said waste paper with a low boilingaliphatic hydrocarbon;

(b) adding sodium hydroxide as a stabilizer to the solution of asphaltin an amount to result in a pH of about 8.5 to about 9.5, whilemaintaining the temperature in steps (a) and (b) below the boiling pointof said hydrocarbon;

(c) maintaining the pH at the range between about 8.5 and about 9.5 byperiodic incremental additions of sodium hydroxide; and

(d) heating the hydrocarbon solution to approximately 200 F.,evaporating sufficient solvent to cause the contaminants to becomedeposited as microscopic particles in dispersion in the waste paper.

3. A process for making pulped waste paper stock which contains asphaltusable by chemical treatment which comprises the steps of:

(a) dissolving the asphalt from said paper stock with a low boilingaliphatic hydrocarbon solvent;

(b) adding tall oil to the dissolved asphalt;

(c) further adding sodium hydroxide as a stabilizer to the resultingasphalt-containing mixture, whereby the solution will have a pH of about8.5 to about 9.5, While maintaining the temperature in steps (a) to ((2)below the boiling point of said solvent;

(d) maintaining the pH at the range between about 8.5

to about 9.5 by periodic incremental additions of sodium hydroxide; and

(e) heating the hydrocarbon solution to approximately 200 F.,evaporating sufficient solvent to cause the contaminants to becomedeposited as microscopic particles in dispersion in the waste paper.

References Cited in the file of this patent UNITED STATES PATENTS

1. A PROCESS FOR MAKING WASTE PAPER, WHICH CONTAINS BITUMINOUSCONTAMINANTS, USABLE BY CHEMICAL TREATMENT, COMPRISING THE STEPS OF: (A)DISSOLVING THE CONTAMINANTS FROM SAID WASTE PAPER WITH AN ALIPHATICHYDROCARBON; (B) ADDING AN ALKALI METAL HYDROXIDE AS A STABILIZER TO THESOLUTION OF CONTAMINANTS, IN AN AMOUNT TO RESULT IN A PH RANGE OF ABOUT8.5 TO ABOUT 9.5; WHILE MAINTAINIING THE TEMPERATURE IN STEPS (A) AND(B) BELOW THE BOILING POINT OF SAID HYDROCARBON; AND (C) HEATING THEHYDROCARBON SOLUTION TO APPROXIMATELY 200*F., EVAPORATING SUFFICIENTSOLVENT TO CAUSE THE CONTAMINANTS TO BECOME DEPOSITED AS MICROSCOPICPARTICLES IN DISPERSION IN THE WASTE PAPER.